TDR水位量測技術在大地/水利工程之應用

Abstract

近年來大地或水利工程之監測系統，使用自動化監測方式來取代手動式量測以成趨勢，尤其是地下水水位之量測。由於傳統的量測感測器（電子式）皆須埋設於孔底（下孔式），不但易受環境之影響且耐久性與準確度更是人質疑。TDR屬於被動式的監測技術，其水位量測的感測器即為傳輸纜線的一部份，主要儀器皆至於地面上（上孔式），感測器本身即為傳輸纜線，沒有其他電子元件，不易損壞、成本低，且由反射波形可檢測感測纜線之狀態，提供自我診斷之功能。 本研究主要的目的，在研發改良現有的TDR水位監測技術，並擴充其在大地與水利工程的應用。在監測技術方面，提出導體絕緣的觀念，及新的自動化資料處理方式，提高水位監測的準確度。此外，亦成功的研發，可同時監測水位與導電度之技術。根據上述感測器的研發成果，本研究進一步發展出水位計、水壓計、雨量計和橋墩沖刷感測器等，亦提出水質監測之改良方式。

Recently automated monitoring system has been widely used in geotechnical or hydraulic engineering, especially in monitoring the ground water level. For those traditional transducers which are mostly berried in the downhole, the durable and accuracy are always being questioned. TDR is a passive monitoring technique in which transmission line is also its sensor when measuring the water level and most of the instrument are set on the uphole side. Therefore there are no other electronic elements which makes the TDR not only is durable and low-coast, but also from its reflection wavefrom TDR can examine the state of the leadcable and provide a self-detective function. The purpose of the study is to improve the technique of water level sensing using TDR,and to further apply this technique in geotechnical and hydraulic engineering. The conductor isolation idea as well as the automatic data processing method has been brought up to enhance the efficiency and accuracy of measurements. Moreover, a method to simultaneously measure the water level and conductivity is proved. According to these results, TDR transducers and installation methods are developed for observational well,pore water pressure, rainfall,and abutment scouring.A potential improvement for water quality monitoring using TDR is also provided.